Dynamic host configuration protocol (DHCP) is a protocol commonly used for controlling the network accessing manner. This protocol is mature, easy to use, and can be supported by most of the computer operating systems. Based on the DHCP protocol, a user terminal may get access to the network after dynamically acquiring an address from an address pool on a DHCP server, and thus the additional dialer configuration and installation are not required, which brings convenience to network administrators and common users.
However, some users, such as leased line users, may expect to use an unchanged address for a period of time, e.g., the user wants to provide diversified services to the public. In this situation, the operator is expected to assign a fixed address to the user, and the user keeps the fixed IP address for an extended period of time by setting a static IP address.
In the prior art, a static IP address binding function is provided for ensuring the access of the leased line users to the network, i.e., the user port and an assigned fixed IP address are bound in the access equipment; after that, the access equipment merely allows messages from the IP address bound with the user port to pass. The access equipment may be an entity, such as a digital subscriber line access multiplexer (DSLAM).
In the prior art, all the binding relations may need corresponding static configurations in the access equipment and is realized manually by the network administrators. Therefore, if the number of the users is quite large, the burden of the network administrator is inevitably increased and the management of the users becomes complicated. Moreover, since the binding relationship always exists in the access equipment, if an invalid user directly uses the bound static IP address to get access to the network, the access equipment cannot determine whether the user is invalid or valid, which may cause the IP address of the valid user to be stolen.